yeah joe i see the pic's you sent
it is older than those i mentioned
i suggested going to a electronics store for a momentary type switch but i see the problem you have is the outer plastic cover is missing too.
like i suggested, find the serial number on the frame, on that truck it should begin with a Nxxxxxx (followed by numbers)

once you have that get with the local yale dealer in your area, they should be able to get you the part numbers you need

unless you find someone with a hardback copy of a manual for those older machines you may not find what you need. The dealer of course would be able to look it up though.